Spatial audio processing, wherein audio signals are processed based on directional information may be implemented within applications such as spatial sound reproduction. The aim of spatial sound reproduction is to reproduce the perception of spatial aspects of a sound field. These include the direction, the distance, and the size of the sound source, as well as properties of the surrounding physical space.
Microphone arrays can be used to capture these spatial aspects. However, often it is difficult to convert the captured signals into a form which preserves the ability to reproduce the event as if the listener was present when the signal was recorded. Particularly, the processed signals often lack spatial representation. In other words the listener may not sense the directions of the sound sources or the ambience around the listener in a way as would be experienced at the original event.
Parametric time-frequency processing methods have been suggested to attempt to overcome these problems. One such parametric processing method, called spatial audio capture (SPAC) is based on analysing the captured microphone signal in the time-frequency domain, and reproducing the processed audio using either loudspeakers or earphones. The perceived audio quality using this method has been found to be good, and the spatial aspects of captured audio signals can be faithfully reproduced.
SPAC was originally developed for using microphone signals from relatively compact arrays, such as mobile devices. However, there is demand to use SPAC with more versatile or geometrically variable arrays. For example a presence-capturing device may contain several microphones and acoustically shadowing objects. Conventional SPAC methods are not suitable for such systems.